Device and method for coating elongate objects
A device for coating an exterior of an elongate object includes a housing structure with an elongate chamber having first and second opposite ends. A port communicates with the first end for receiving the elongate object and an outlet is located at the second end. An air supply passage and a coating material supply passage communicate with the elongate chamber. Pressurized air and coating material are adapted to enter the elongate chamber through the air supply passage and the coating material supply passage, respectively, to form a mist in the elongate chamber moving toward the outlet while coating the exterior of the object. A method of coating an exterior surface of the elongate object with the coating material includes holding the elongate object lengthwise in the elongate chamber, mixing the pressurized air and the coating material to form a mist, and coating the exterior surface while directing the mist around the exterior surface and toward the outlet of the elongate chamber.
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The present invention generally relates to the application of coatings onto exterior surfaces of objects and, more specifically, the coating of elongate objects such as needles.
BACKGROUNDElongate objects are coated with material for various reasons. For example, hypodermic needles are often coated with lubricious or friction-reducing materials, such as silicone based oils. This provides a low friction outer surface of the needle for purposes of easing the introduction of the needle through the skin of a patient. Various methods and apparatus for applying the coating material to the needle have been used in the past. These include dipping methods in which the needles are dipped lengthwise into a bath containing silicone and solvent. This method presents difficulties and challenges related to handling the silicone and solvents, as well as the lengthy drying times involved, and the ventilation needs due to the use of the solvents.
Other methods that have been employed in the past involve various manners of spraying the coating material onto the needle. Typically, the spraying device will discharge the coating material in a single direction and the material will not flow around the entire exterior of the needle. For this reason, the needle and/or spray dispenser must be rotated to evenly distribute the coating material on the entire exterior surface of the needle. Alternatively, multiple spraying devices may be used to coat all sides of the needle. Either case involves increased complication and expense. The overspray or mist can also present problems in the environment around the equipment or require apparatus for containing the overspray. Due to the viscosity of the fluid coating material, it can also be difficult to achieve the required thin, uniform layer of coating material on the exterior surface of the needle.
It would therefore be desirable to provide a device and method for easily coating an exterior of an elongate workpiece, such as a needle, while addressing various challenges presented by past devices and methods.
SUMMARYThe present invention generally provides a device for coating an exterior of an elongate object. The device generally comprises a housing structure including an elongate coating chamber having first and second opposite ends. A port communicates with the first end for receiving the elongate object into the coating chamber and an outlet at the second end. The coating chamber has at least first and second sections. The first section is located closer to the outlet than the second section and the first section has a greater cross sectional area than the second section. The housing structure further includes an air supply passage and a coating material supply passage communicating with the elongate coating chamber. The pressurized air and coating material are adapted to enter the elongate chamber through the air supply passage and the coating material supply passage, respectively, to form a mist of the air and coating material. This mist is directed into the elongate chamber and generally toward the outlet while coating the exterior of the elongate object inserted into the elongate chamber through the port.
In a more specific embodiment, a mixing passage communicates with the air supply passage and the coating material supply passage. The mixing passage further communicates with the elongate chamber. The pressurized air and the coating material enter the mixing passage through the air supply passage and the coating material supply passage, respectively, and the mist of the air and coating material begins to form in the mixing passage before entering the elongate chamber.
A device constructed according to the exemplary embodiment further includes various additional features. For example, a valve comprised of a valve member and a valve seat selectively supplies the coating material to the elongate chamber. A ring shaped structure communicates between the air supply passage and the mixing passage. The ring shaped structure is configured to cause the pressurized air to enter the mixing passage with a swirling motion about a discharge location of the coating material into the mixing passage. The ring shaped further includes a central passage through which the coating material is directed into the mixing passage and into the air moving with the swirling motion. The device may further include a coating material injecting element including a tube with an outlet. The tube extends through the central passage with the outlet of the tube positioned in the mixing passage. The ring shaped structure more specifically includes a ring shaped wall surrounding an inner space and disposed around a central axis. The central passage extends along the central axis. The ring shaped wall further includes a plurality of air directing passages communicating between the air supply passage and the inner space so as to achieve the swirling motion around the central axis. The ring shaped structure further comprises a plurality of stand-off elements forming additional air passages between the stand-off elements and providing communication between the air supply passage and the mixing passage.
The elongate chamber is preferably configured with increasing diameter in a direction from the first end to the second end so that an increase in pressure is achieved in this direction within the chamber. The flow of the mist is generally along a central axis of the elongate chamber coaxial with the port at the first end. The mixing passage extends transverse, and more preferably perpendicular, to the elongate chamber.
The elongate object further comprises a hollow needle having opposite, open ends, such as a hypodermic syringe needle. The device further comprises a needle holder including an interior air space and a needle holding element configured to secure a first end of the needle in communication with the interior air space. The open second end of the needle extends outwardly from the needle holder for insertion through the port and into the elongate chamber. The interior air space is adapted to be pressurized with air to force air through the needle during a coating operation and prevent clogging of the open second end of the needle with the coating material.
In another aspect, a method is provided for coating an exterior surface of an elongate object with a coating material. The method generally includes holding the elongate object lengthwise in an elongate chamber having first and second opposite ends and an outlet at the second end. A mist is formed from a mixture of the air and the coating material and the exterior surface is coated with the coating material while directing the mist around the exterior surface of the elongate object and toward the outlet of the elongate chamber.
The method practiced according to an illustrative example includes various additional aspects and steps. For example, the pressurized air and the coating material are first mixed within a mixing passage oriented transverse to the elongate chamber prior to directing the air and the coating material into the elongate chamber as a mist. The mixing passage extends along an axis and the method further comprises swirling the air around the axis of the mixing passage at an air inlet to the mixing passage, and directing the coating material into the mixing passage along the central axis to mix with the swirling air. The method further comprises directing the air into the mixing passage with a Venturi effect. Holding the elongate object further comprises directing the object through a port at the first end of the elongate chamber and the method further comprises directing additional air through the port and adjacent the object toward the outlet of the elongate chamber. The elongate object further comprises a hollow needle with opposite, first and second open ends, and the method further comprises directing air through the first open end of the needle and out of the second open end positioned in the elongate chamber to prevent clogging of the first open end with the coating material. Directing the coating material into the elongate chamber further comprises actuating a valve to allow pressurized coating material to flow into the elongate chamber. The coating material may be a friction reducing material, such as a material containing silicone.
Various additional features and advantages of the invention will become more apparent to those of ordinary skill in the art upon review of the following detailed description of the illustrative embodiments taken in conjunction with the accompanying drawings.
Referring to
A mixing passage 52 in the first sub-housing 22 extends transverse and, more specifically, perpendicular to the elongate chamber 30. This mixing passage 52 communicates directly with the smallest diameter chamber portion 30a adjacent the insert 44 and needle port 35. As best shown in
The coating material is provided from a suitable pressurized supply 72 (
More specifically referring to
Referring to
The first sub-housing 22 may be removed from the second sub-housing 24 for repair and replacement purposes. More specifically, components contained in the first sub-housing 22 may become contaminated due to the environmental air that is being suctioned into the passages of those components and mixed with the coating material. On the other hand, the components and passages associated with the second sub-housing 24 need much less service during regular use. Thus, the second sub-housing 24 and its associated components may remain mounted while the first sub-housing 22 and its attached components are removed from the second sub-housing by removing fasteners 26. The components 44, 46, 54, 58 associated with the first sub-housing 22 may be easily disassembled for cleaning purposes. In addition, the modular nature of the first sub-housing 22 allows different application requirements to be accommodated, such as size changes to accommodate different elongate objects, and adjustments to the type and/or viscosity of coating material. In addition, the injecting element 58 may be replaced to accommodate a coating material having a different viscosity. Finally, the insert 44 receiving the elongate object 36 may be modified for particular applications, such as coating operations of syringe tips with various configurations.
While the present invention has been illustrated by a description of various preferred embodiments and while these embodiments have been described in some detail, it is not the intention of the Applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The various features of the invention may be used alone or in any combination depending on the needs and preferences of the user. This has been a description of the present invention, along with the preferred methods of practicing the present invention as currently known. However, the invention itself should only be defined by the appended claims.
Claims
1. A device for coating an exterior of an elongate object, comprising:
- a housing structure including an elongate coating chamber having first and second opposite ends, a port communicating with said first end for receiving the elongate object into the coating chamber and an outlet at said second end, said elongate coating chamber having at least first and second sections, said first section located closer to said outlet than said second section and said first section having a greater cross sectional area than said second section, the housing structure further including an air supply passage and a coating material supply passage communicating with said elongate coating chamber; and
- a ring shaped structure communicating between said air supply passage and said elongate coating chamber, said ring shaped structure configured to cause a swirling motion of the pressurized air;
- wherein pressurized air and coating material are adapted to enter said elongate coating chamber through said air supply passage and said coating material supply passage, respectively, to form a mist of the air and coating material that is directed into said elongate coating chamber and generally toward said outlet while coating the exterior of the elongate object inserted into said elongate coating chamber through said port; and wherein said ring shaped structure further includes a central passage through which the coating material is adapted to be directed into the air moving with the swirling motion to thereby form the mist.
2. The device of claim 1, further comprising:
- a mixing passage communicating with said air supply passage and said coating material supply passage, said mixing passage further communicating with said elongate coating chamber, wherein pressurized air and coating material are adapted to enter said mixing passage through said air supply passage and said coating material supply passage, respectively, to form the mist of the air and coating material that is directed into said elongate coating chamber and generally toward said outlet while coating the exterior of the object inserted into said elongate coating chamber through said port.
3. The device of claim 2, wherein said elongate coating chamber includes a central axis coaxial with said port, and said mixing passage extends transverse to said elongate coating chamber.
4. The device of claim 1, further comprising a coating material injecting element including a tube with an outlet, said tube extending through said central passage.
5. The device of claim 4, wherein said ring shaped structure further comprises a ring shaped wall surrounding an inner space and disposed around a central axis, and wherein said central passage extends along the central axis, said ring shaped wall further including a plurality of air directing passages communicating between said air supply passage and said inner space and directing the pressurized air into said inner space in the swirling motion around said central axis.
6. The device of claim 1, wherein said ring shaped structure further comprises a plurality of stand-off elements forming additional air passages communicating between said air supply passage and said elongate coating chamber.
7. The device of claim 1, further comprising:
- a valve member and a valve seat mounted in said coating material supply passage, said valve member movable with respect to said valve seat to selectively supply the coating material to the elongate coating chamber.
8. The device of claim 7, wherein said housing structure further comprises a first sub-housing and a second sub-housing, said first sub-housing being removably coupled to said second sub-housing and containing said elongate coating chamber, and said second sub-housing containing said valve member and said valve seat.
9. The device of claim 1, wherein the elongate object further comprises a hollow needle, and further comprising:
- a needle holder including an interior air space and a needle holding element configured to secure a first end of the needle in communication with the interior air space while an open second end of the needle extends outwardly from said needle holder for insertion through said port and into said elongate coating chamber, wherein said interior air space is adapted to be pressurized with air to force air through the needle and prevent clogging of the open second end of the needle with the coating material.
10. The device of claim 1, wherein said port is configured to allow additional air to be drawn into said elongate coating chamber as the mist is coating the exterior of the elongate object.
11. A device for coating an exterior of an elongate object, comprising:
- a housing structure including an elongate coating chamber having first and second opposite ends, said elongate coating chamber including a port communicating with said first end for receiving the elongate object and an outlet at said second end, an air supply passage, a coating material supply passage, and a mixing passage communicating with said air supply passage and said coating material supply passage, said mixing passage further communicating with said elongate coating chamber; and
- a ring shaped structure communicating between said air supply passage and said mixing passage, said ring shaped structure configured to cause the pressurized air to enter said mixing passage with a swirling motion, said ring shaped structure further including a central passage through which the coating material is directed into said mixing passage and into the air moving with the swirling motion;
- wherein the pressurized air and coating material in said mixing passage form a mist in said elongate coating chamber moving toward said outlet while coating the exterior of an object inserted into said elongate coating chamber through said port.
12. The device of claim 11, wherein said ring shaped structure further comprises a ring shaped wall surrounding an inner space and disposed around a central axis, and wherein said central passage extends along the central axis, said ring shaped wall further including a plurality of air directing passages communicating between said air supply passage and said inner space and directing the pressurized air into said inner space in the swirling motion around the central axis.
13. The device of claim 12, wherein said ring shaped wall further comprises a plurality of stand-off elements forming additional air passages communicating between said air supply passage and said mixing passage.
14. The device of claim 11, further comprising a coating material injecting element including a tube with an outlet, said tube extending through said central passage with said outlet positioned in said mixing passage.
15. The device of claim 11, further comprising:
- a valve member and a valve seat mounted in said coating material supply passage, said valve member movable with respect to said valve seat to selectively supply the coating material to the elongate coating chamber.
16. The device of claim 11, wherein said port is configured to allow additional air to be drawn into said elongate coating chamber as the mist is coating the exterior of the elongate object.
17. The device of claim 11, wherein said elongate coating chamber includes a central axis coaxial with said port, and said mixing passage extends transverse to said elongate coating chamber.
18. The device of claim 11, wherein the elongate object further comprises a hollow needle, and further comprising:
- a needle holder including an interior air space and a needle holding element configured to secure a first end of the needle in communication with the interior air space while an open second end of the needle extends outwardly from said needle holder for insertion through said port and into said elongate coating chamber, wherein said interior air space is adapted to be pressurized with air to force air through the needle and prevent clogging of the open second end of the needle with the coating material.
19. The device of claim 11, wherein said ring shaped structure includes an air passage forming a constriction into said mixing passage thereby causing a Venturi effect of the air entering said mixing passage.
20. The device of claim 11, further comprising:
- a valve member and a valve seat mounted in said coating material supply passage, said valve member movable with respect to said valve seat to selectively supply the coating material to the elongate coating chamber.
21. The device of claim 20, wherein said housing structure further comprises a first sub-housing and a second sub-housing, said first sub-housing being removably coupled to said second sub-housing and containing said mixing passage, said ring shaped structure and said elongate coating chamber, and said second sub-housing containing said valve member and said valve seat.
22. The device of claim 11, wherein said port is configured to allow additional air to be drawn into said elongate coating chamber as the mist is coating the exterior of the elongate object.
23. A device for coating an exterior of an elongate object, comprising:
- a housing structure including an elongate coating chamber having first and second opposite ends, a port communicating with said first end for receiving the elongate object into the coating chamber and an outlet at said second end, the housing structure further including an air supply passage and a coating material supply passage communicating with said elongate coating chamber; and
- an air swirling structure communicating between said air supply passage and said elongate coating chamber, said air swirling structure configured to cause a swirling motion of the pressurized air;
- wherein pressurized air and coating material are adapted to enter said elongate coating chamber through said air supply passage and said coating material supply passage, respectively, to form a mist of the air and coating material that is directed into said elongate coating chamber and generally toward said outlet while coating the exterior of the elongate object inserted into said elongate coating chamber through said port; and wherein said air swirling structure further includes a central passage through which the coating material is adapted to be directed into the air moving with the swirling motion to thereby form the mist.
24. The device of claim 23, said elongate coating chamber having at least first and second sections, said first section located closer to said outlet than said second section and said first section having a greater cross sectional area than said second section.
25. The device of claim 23, further comprising a mixing passage communicating with said air supply passage and said coating material supply passage, said coating material supply passage extending within said mixing passage and including an outlet in said mixing passage, said mixing passage further communicating with said elongate coating chamber, wherein pressurized air and coating material are adapted to enter said mixing passage through said air supply passage and said coating material supply passage, respectively, to form the mist of the air and coating material that is directed into said elongate coating chamber and generally toward said outlet while coating the exterior of the object inserted into said elongate coating chamber through said port.
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Type: Grant
Filed: May 24, 2011
Date of Patent: Jun 24, 2014
Patent Publication Number: 20120301613
Assignee: Nordson Corporation (Westlake, OH)
Inventors: Andreas Doker (Munich), Thomas Wanka (Kaufbueren), Michael Wilczek (Germering)
Primary Examiner: Yewebdar Tadesse
Application Number: 13/114,300
International Classification: B05B 13/02 (20060101); B05B 1/28 (20060101); B05B 15/04 (20060101);